1. Field of the Invention
The present invention relates to the channel allocating technologies, and the base station technologies and communications technologies utilizing the channel allocating technologies. The present invention particularly relates to a channel allocating method according to the type of application used in a terminal, and a base station apparatus and its communication system utilizing the channel allocating method.
2. Description of the Related Art
Various types of non-voice Communications such as the transmission of images are in practice owing to the growing multimedia services. The amount of information in this non-voice communication varies, but there is a basic demand where the variation in the transmission time be minimized. For example, if the reproduction of the moving image streaming is to be carried out in the non-voice communication, the amount of information in the moving image data varies according to the variation of the images, so that it is desirable that the variation in the transmission time be minimized in order for the images to be smoothly reproduced at a receiving end. In addition to the transmission time, it is also required that a predetermined transmission quality, namely, the so-called communication quality be satisfied.
As an approach for meeting the above-described requirements, there is available a method in which the transmission speed between a base station apparatus and a terminal apparatus is determined according to the amount of information to be transmitted, namely, the size of a packet. That is, the transmission rate is raised as the packet size becomes large whereas it is reduced as the packet size becomes small. Thereby, the variation of transmission time between the base station apparatus and the terminal apparatus is kept small. Reference (1) in the following Related Art List serves as an example for such a conventional method.
Related Art List
(1) Japanese Patent Application Laid-Open No. 2002-374321.
In a case where the information to be handled by the non-voice communication is the moving image streaming, desired is the smaller variation in the transmission rate. In the case of video conference, it is further requested that the transmission time itself be generally small. On the other hand, if the information to be handled by the communication is data for file transfer or Web browser, the accuracy of transmitted data is most critically required rather than the transmission time. In this manner, the requirements for the communication quality differ according to application used in the terminal apparatus. In general, the base station apparatus connects a plurality of terminal apparatuses by multiplexing, and communicates with them by allocating predetermined channels to the respective terminal apparatuses. Thus, the limited wireless resources are used among the plurality of terminal apparatuses. In such a situation, when many wireless resources are used in order to reduce the transmission time while a predetermined terminal apparatus is performing the file transfer, the streaming reproduction by other terminal apparatus may not be performed in a desired manner. Moreover, if a communication means between the base station apparatus and the terminal apparatus is wireless communication, it is possible that the characteristics of propagation paths may have an adverse effect on the communication.